Currently, mobile communication technologies are evolving towards higher frequency, larger carrier bandwidth, higher data rate and more heterogeneous layers. Future mobile networks, e.g., the 5th Generation (5G) mobile networks, are likely to be a combination of the 3rd Generation (3G) technologies, the 4th Generation (4G) technologies and new features such as Ultra-Density Network (UDN) or millimeter Wave Radio Access Technology (mmW-RAT).
FIG. 1 shows an exemplary structure of a mobile network. As shown in FIG. 1, a cluster of Access Nodes (ANs) 104 and 106 are connected to and controlled by a coordinator node referred to as Central Control Unit (CCU) 102. User devices 110, 112, 114 and 116 are served by the AN 104 and a user device 118 is served by the AN 106.
In a mobile network, one carrier may consist of a number of sub-carriers. Each sub-carrier can have a certain bandwidth, e.g. 100 MHz, and the total carrier bandwidth can be up to 1 GHz or even higher. FIG. 2 illustrates an exemplary carrier containing 4 sub-carriers. In FIG. 2, the smallest resource grid in time and frequency is referred to as a resource element (RE) or an Atomic Scheduling Unit (ASU).
Conventionally, there are two major types of resource allocation schemes. The first one is known as contention based resource allocation, which is typically used in e.g., Wi-Fi networks. In Wi-Fi networks, resources for transmission of control channels are fully shared with resources for data transmission. Further, there is no fixed frame structure in Wi-Fi networks and thus a control channel may occupy the entire network bandwidth, resulting in a high control overhead and lack of flexibility and efficiency in resource utilization. The second one is known as scheduling based resource allocation, which is typically used in cellular networks such Long Term Evolution (LTE) network. In the LTE network, resource allocation for control channels is quite static and cannot be flexibly adapted to changes in network conditions.
There is thus a need for an improved solution for resource allocation for control channels.